Conventionally, a solid-state imaging apparatus capable of realizing a high dynamic range (HDR) by using pixel groups having different optical sensitivities has been proposed. With respect to a part having a small incident light amount, a pixel group having a high optical sensitivity can obtain image information with sharper contrast than a pixel group having a low optical sensitivity. In the pixel group having the high optical sensitivity, if an incident light amount is large, a signal output is saturated with respect to an incident light amount and thus output characteristics may deteriorate. With respect to a part having a large incident light amount, by using an output by a pixel group having a low optical sensitivity, it is possible to ensure image reproducibility. A solid-state imaging apparatus can obtain a HDR image by synthesizing parts having good output characteristics from an image.
The solid-state imaging apparatus multiples a signal value obtained by the pixel group having the low optical sensitivity by predetermined gain, in order to equalize output levels of the pixel group having the high optical sensitivity and the pixel group having the low optical sensitivity. For example, a solid-state imaging apparatus having a complementary metal oxide semiconductor (CMOS) sensor mounted thereon can obtain a configuration for synthesizing HDR images by multiplying a digital type image signal by digital gain by an image processing circuit formed integrally with the CMOS sensor.
For synthesis of the HDR image, the solid-state imaging apparatus requires a line memory for holding an image signal. In addition, the solid-state imaging apparatus may be provided with a line memory for a noise cancellation process of reducing noise such as random noise or defect correction of a damaged part (hereinafter, referred to as defect) of a digital image signal by pixels which do not normally function. In the solid-state imaging apparatus, by increasing necessary line memories, a circuit size increases and cost increases. In the solid-state imaging apparatus, if defect correction or noise cancellation process is reduced in order to reduce a circuit size, a merit such as high quality may be damaged.
With respect to such problems, a configuration for synthesizing HDR images may be mounted in a digital signal processor (DSP) located at a next stage of the solid-state imaging apparatus instead of mounted in the solid-state imaging apparatus. However, in order to cope with HDR, versatility of the DSP deteriorates and system costs increase. Thus, overall costs of a camera module increase.